This invention relates to detergent compositions having significantly improved calcium sequestration capacity as well as superior builder capacity in comparison to conventional aluminosilicate builder materials, while not redepositing on fabrics. More particularly, this invention relates to detergent compositions comprising microclusters of submicron crystallites of an aluminosilicate ion exchange material.
The presence of hardness ions (i.e. Ca+2, Mg+2) during the laundering process has long been recognized to negatively impact the cleaning performance of detergents. It is also known that faster sequestration of calcium and magnesium yields improved cleaning performance.
The primary function of inorganic builders such as zeolites in detergents is to remove hardness ions in the wash water via ion-exchange processes and thus improve the cleaning performance of the detergent. For a zeolite to be an effective builder the ion exchange must take place within the relatively short time frame of a wash cycle, typically 10-12 minutes. More importantly the hardness level must be reduced in the first 0-5 minutes to significantly improve the cleaning performance of the detergent composition.
Despite the long history of zeolite A and the more recent development of relatively costly alternatives such as zeolite AX, the current zeolite builder systems remain deficient in their ability to efficiently sequester large enough volumes of hardness ions in a relatively short period of time (i.e. 0-5 minutes). This is a result of the fact that the diffusional paths of hardness ions within currently available zeolite crystals are too long. Under actual wash conditions, wherein the wash solution is between 20xc2x0 C.-40xc2x0 C., equilibrium times for calcium exchange are typically much greater than five minutes for commercially available zeolite A. At lower temperatures ( less than 20xc2x0 C.) the rate of ion exchange is slowed even further, such that the calcium level never equilibrates in the time frame of a typical wash cycle.
Many attempts have been made in the art to solve the problems described above. Attempts have been made at using small particle size zeolite A. However, this approach introduced new problems. When conventional zeolite A particles are simply ground up into smaller particles they exhibit slightly improved kinetics under typical wash conditions. However, the small particles deposit on the surface of fabrics and because of their small size are not removed by the washing process. After a number of wash cycles this leads to an undesirable white buildup on fabrics. Additionally, these small particle size zeolites do not provide improved kinetics in stressed wash conditions with temperatures below 25xc2x0 C. and high water hardness.
Accordingly the need remains for an inorganic builder/zeolite material that provides rapid reduction in the level of free hardness in the wash water, most preferably in the first 2-3 minutes of the wash cycle. There is also a need for an inorganic builder/zeolite material capable of delivering improved hardness ion sequestration capacity, low redeposition and superior builder capacity, especially at low temperatures. These new materials must also remain compatible with existing process techniques and safety/handling issues.
Additionally, the need also exists for a zeolite material which simultaneously embodies the low redeposition property of conventional large particle size zeolite A and the improved kinetics and builder capacity of small particle size zeolites. These problems are solved by the present invention.
The present invention meets the aforementioned needs by providing a detergent composition with superior hardness ion sequestration capacity while maintaining or improving cleaning performance, especially at low temperatures. This is achieved by providing a detergent composition comprising microclusters of an aluminosilicate ion exchange material. According to a first embodiment of the present invention a detergent composition comprises a detersive surfactant system, a zeolite system comprising microclusters of submicron crystallites of an aluminosilicate ion exchange material selected from the group consisting of zeolite A, zeolite X, zeolite Y, chabazite and mixtures thereof and conventional aluminiosilicate materials other than those comprising the microclusters and detergent adjunct materials, including but not limited to conventional builders, chelants, brighteners, bleaching agents, enzymes, soil release polymers, dye transfer inhibitors, fillers, perfumes, and mixtures thereof. Preferably the detersive surfactant system is present at about 0.1% to about 95% by weight of the total composition and the total zeolite system is present at about 5% to about 75% by weight of the total composition, the balance being one or more detergent adjuncts. The zeolite system comprises from about 25% to about 100%, preferably from about 50% to about 100%, microclusters according to the present invention and from about 0% to about 75%, preferably from about 0% to about 50%, conventional aluminosilicate materials other than those comprising the microclusters.
The present invention also provides a method for sequestering hardness ions in wash water at significantly increased speed. The method comprises the step of preparing a detergent composition containing microclusters of submicron crystallites of an aluminosilicate ion exchange material selected from the group consisting of zeolite A, zeolite X, zeolite Y, chabazite and mixtures thereof, and contacting said detergent composition with clothes.
All percentages, ratios, and proportions herein are on a weight basis unless otherwise indicated. All documents cited are hereby incorporated by reference in their entirety.